OR/15/035 Appendix 1

Thompson, J F. 2015. Model metadata report for HS2 Area 4. British Geological Survey Internal Report, OR/15/035.

Modelling notes

HS2_Area4_Route_JT

03 April 2014
11:42

03/04/2014

HS2_Area4_NWSE_Section2

03 April 2014
13:53

Surface geology suggests folding within the DYS-MRB-WHM although this is not marked on the map (around Cropredy Lawn/Beecham's cottages), this may fit in with localised faulting. It is unclear from the fieldslip what evidence was used — there is a borehole (#88 on field slip, SP44NE73, 331590) which has 2' soil, 3' yellow clay, 85' blue clay/lmst). This would suggest possibly a valley head overlying CHAM. Fieldslips illegible! But the hand drawn contours suggest that the geologist was fitting the outcrop to the contours which aren't quite correct. WHM outcrop possibly should be on top of the small hill instead?

16/04/2014

Faulting — check how deep likely to go. Banbury fault (on Banbury sheet but not within model area, stops within Charmouth mudstone according to 50K sheet cross section).

Need to add in BCMU below BAN

HS2_Area4_NWSE_Section4

03 April 2014
15:12

Dips of deeper units arbitrarily adjusted to account for change in section direction.

Outcrop of DYS in valley near Byfield does not fit with borehole info or topo so I have left it out.

General — all sections

03 April 2014
17:09

Deeper geology in all sections taken from boreholes where possible but roughly tracked along elsewhere.

HS2_Area4_NWSE_Section10_JT

03 April 2014
17:09

Mapping and borehole do not agree in extent of WHM.

HS2_Area4_NESW_Section5

28 May 2014
11:49

The throw on the fault at the western end of this section is unclear - it changes along its length

HS2_Area4_ROUTE_JT

26 June 2014
16:06

Completing this (straight) section showed a kink in the CHAM halfway along the section (at HS2_Area4_NESW_Section4)which I have straightened out and will use to adjust other sections.

Edge matching with Keith

10 July 2014
10:04

Section8_KA thicknesses at eastern end not as expected

Inconsistent naming — what is SASH? Salford Shale, lower part of BLI — dies out in northern part of Area 4.

Faulting in northeast corner?? Not sure, KAM to investigate.

LPMB/RLS equivalent to BLI and WLI?? WLI = Langport Member (LPMB), BLI = SASH and RLS

04/09/2014

Edge matching issues — talk to Keith about his section 18, borehole 332324 — why has he not used the level for PNG?

Section 7 *Check

10 July 2014
17:08

Something not right now I have snapped to KAM's sections — check.

HS2_AREA4_NESW_Section3

30 July 2014
14:01

Re-do? Dog-leg in section is not reflected in units.

Section 8

30 July 2014
14:46

Check dip of upper units at western end. Adjusted to be more level.

HS2_Area4_NWSE_Section1

04 September 2014
13:31

Adjusted LPMB

Outcrop changes

11 September 2014
15:11

MRB on section 11, adjusted slightly to fit in with alluvium